To start tracking, open a web browsing app on your iPhone or iPad (Safari and Chrome support the mobile optimized tracker), and then visit the official website for Google Santa Tracker. On both mobile and desktop, the site will show you a live map of Santa's location, his next stop, a live video feed of his trip, and an estimated arrival time for your area.
If you scroll down you can see pictures of the places he's already visited, more details about these locations, a live count of the gifts he's delivered, and more. Google last year added these features into its main Google Maps app for iOS, but as of writing the Santa tracker does not appear to be in the iOS app this year.
Of course, there are plenty of other Santa tracking services and apps on the App Store, including NORAD Tracks Santa Claus [Direct Link]. NORAD's Santa tracking app is mainly a countdown timer that links you out to the mobile web when you want to start tracking the journey.
Similar to Google, NORAD details where Santa was last seen, where he's heading to next, and how many gifts he's delivered. You can also interact with a 360-degree video feed of Santa's sleigh as he makes his journey around the Earth. If you're on Mac or other desktop computers, you can visit NORAD's full Santa tracking website right here.
At the time of writing, Santa was last seen over the Andaman Sea and heading to Thailand.